Patterning process and chemical amplified photoresist with a photodegradable base

ABSTRACT

A method for fabricating an integrated circuit device is disclosed. The method includes providing a substrate; forming a first material layer over the substrate; forming a second material layer over the first material layer, wherein the second material layer comprises a photodegradable base material; and exposing at least a portion of the second material layer.

BACKGROUND

The semiconductor integrated circuit (IC) industry has experienced rapidgrowth. Technological advances in IC materials and design have producedgenerations of ICs where each generation has smaller and more complexcircuits than the previous generation. In the course of IC evolution,functional density (i.e., the number of interconnected devices per chiparea) has generally increased while geometry size (i.e., the smallestcomponent (or line) that can be created using a fabrication process) hasdecreased. This scaling down process generally provides benefits byincreasing production efficiency and lowering associated costs. Suchscaling down has also increased the complexity of processing andmanufacturing ICs and, for these advances to be realized, similardevelopments in IC processing and manufacturing are needed. For example,conventional photoresist layers comprise a non-photodegradable base. Thenon-photodegradable base is not photosensitive, and thus, after anexposure process, exposed areas of a photoresist layer exhibit less thandesirable acid distribution contrast and base distribution contrast.This leads to lower pattern contrast, resulting in poor patternprofiles, particularly as pattern features continue to decrease in size.

Accordingly, what is needed is a method and photoresist material formanufacturing an integrated circuit device that addresses the abovestated issues.

SUMMARY

A photoresist material for semiconductor device patterning processes isprovided. The photoresist material comprises a polymer, a photoacidgenerator, a quencher base, an electron acceptor, and a photodegradablebase. The photodegradable base comprises an amine linked with afunctional group comprising substantially delocalizable pi electrons bya —C— group. The photoresist material may further comprise at least oneof a chromophore, a solvent, a surfactant, and/or crosslinker.

A method for fabricating an integrated circuit device is also disclosed.The method includes providing a substrate; forming a first materiallayer over the substrate; forming a second material layer over the firstmaterial layer, wherein the second material layer comprises aphotodegradable base material; and exposing at least a portion of thesecond material layer.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is best understood from the following detaileddescription when read with the accompanying figures. It is emphasizedthat, in accordance with the standard practice in the industry, variousfeatures are not drawn to scale and are used for illustration purposesonly. In fact, the dimensions of the various features may be arbitrarilyincreased or reduced for clarity of discussion.

FIG. 1 is a flow chart of a method for fabricating a semiconductordevice according to aspects of the present embodiments.

FIGS. 2A-2C are various cross-sectional views of embodiments of asemiconductor device during various fabrication stages according to themethod of FIG. 1.

DETAILED DESCRIPTION

The present disclosure relates generally to methods for manufacturingsemiconductor devices, and more particularly, to a method andphotoresist for patterning various semiconductor device features.

It is understood that the following disclosure provides many differentembodiments, or examples, for implementing different features of theinvention. Specific examples of components and arrangements aredescribed below to simplify the present disclosure. These are, ofcourse, merely examples and are not intended to be limiting. Forexample, the formation of a first feature over or on a second feature inthe description that follows may include embodiments in which the firstand second features are formed in direct contact, and may also includeembodiments in which additional features may be formed between the firstand second features, such that the first and second features may not bein direct contact. In addition, the present disclosure may repeatreference numerals and/or letters in the various examples. Thisrepetition is for the purpose of simplicity and clarity and does not initself dictate a relationship between the various embodiments and/orconfigurations discussed.

With reference to FIG. 1 and FIGS. 2A-2C, a method 100 and asemiconductor device 200 are collectively described below. Thesemiconductor device 200 may be an integrated circuit, or portionthereof, that may comprise memory cells and/or logic circuits. Thesemiconductor device 200 may include passive components such asresistors, capacitors, inductors, and/or fuses; and active components,such as P-channel field effect transistors (PFETs), N-channel fieldeffect transistors (NFETs), metal-oxide-semiconductor field effecttransistors (MOSFETs), complementary metal-oxide-semiconductortransistors (CMOSs), high voltage transistors, and/or high frequencytransistors; other suitable components; and/or combinations thereof.FIG. 1 is a flow chart of one embodiment of the method 100 for makingthe semiconductor device 200. FIGS. 2A-2C are various cross-sectionalviews of the semiconductor device 200 according to one embodiment, inportion or entirety, during various fabrication stages of the method100. It is understood that additional steps can be provided before,during, and after the method 100, and some of the steps described belowcan be replaced or eliminated, for additional embodiments of the method.It is further understood that additional features can be added in thesemiconductor device 200, and some of the features described below canbe replaced or eliminated, for additional embodiments of thesemiconductor device 200.

The method 100 is a lithography method for use in manufacturing asemiconductor device. The terms lithography, immersion lithography,photolithography, and optical lithography may be used interchangeably inthe present disclosure. Photolithography is a process used inmicrofabrication, such as semiconductor fabrication, to selectivelyremove parts of a thin film or a substrate. The process uses light totransfer a pattern (e.g., a geometric pattern) from a photomask to alight-sensitive layer (e.g., photoresist, or simply “resist”) on thesubstrate. The light causes a chemical change in exposed regions of thelight-sensitive layer, which may increase or decrease solubility of theexposed regions. If the exposed regions become more soluble, thelight-sensitive layer is referred to as a positive photoresist. If theexposed regions become less soluble, the light-sensitive layer isreferred to as a negative photoresist. Baking processes, such as apost-exposure bake (PEB) or pre-exposure bake, may be performed beforeor after exposing the substrate. A developing process selectivelyremoves the exposed or unexposed regions to a developing solutioncreating an exposure pattern over the substrate. A series of chemicaltreatments then engrave the exposure pattern into the substrate (ormaterial layer), while the patterned photoresist protects regions of theunderlying substrate (or material layer). Alternatively, metaldeposition, ion implantation, or other processes can be carried out.Finally, an appropriate reagent removes (or strips) the remainingphotoresist, and the substrate is ready for the whole process to berepeated for the next stage of circuit fabrication. In a complexintegrated circuit (for example, a modern CMOS), a substrate may gothrough the photolithographic cycle a number of times.

Referring to FIGS. 1 and 2A, the method 100 begins at step 102 wherein asubstrate 210 is provided. The substrate 210 is a semiconductorsubstrate. The substrate 210 comprises an elementary semiconductorincluding silicon and/or germanium in crystal; a compound semiconductorincluding silicon carbide, gallium arsenic, gallium phosphide, indiumphosphide, indium arsenide, and/or indium antimonide; an alloysemiconductor including SiGe, GaAsP, AlInAs, AlGaAs, GaInAs, GaInP,and/or GaInAsP; or combinations thereof. The alloy semiconductorsubstrate may have a gradient SiGe feature in which the Si and Gecomposition change from one ratio at one location to another ratio atanother location of the gradient SiGe feature. The alloy SiGe may beformed over a silicon substrate. The SiGe substrate may be strained.Furthermore, the semiconductor substrate may be a semiconductor oninsulator (SOI). In some examples, the semiconductor substrate mayinclude a doped epi layer. In other examples, the silicon substrate mayinclude a multilayer compound semiconductor structure. Alternatively,the substrate 210 may include a non-semiconductor material, such as aglass substrate for thin-film-transistor liquid crystal display(TFT-LCD) devices, or fused quartz or calcium fluoride for a photomask(mask).

The substrate 210 may comprise one or more material layers. The one ormore material layers may comprise one or more high-k dielectric layers,gate layers, hard mask layers, interfacial layers, capping layers,diffusion/barrier layers, dielectric layers, conductive layers, othersuitable layers, and/or combinations thereof. A high-k dielectric layermay comprise hafnium oxide (HfO₂), hafnium silicon oxide (HfSiO),hafnium silicon oxynitride (HfSiON), hafnium tantalum oxide (HfTaO),hafnium titanium oxide (HfTiO), hafnium zirconium oxide (HfZrO), metaloxides, metal nitrides, metal silicates, transition metal-oxides,transition metal-nitrides, transition metal-silicates, oxynitrides ofmetals, metal aluminates, zirconium silicate, zirconium aluminate,zirconium oxide, titanium oxide, aluminum oxide, hafnium dioxide-alumina(HfO₂—Al₂O₃) alloy, other suitable high-k dielectric materials, and/orcombinations thereof. A gate layer may comprise silicon-containingmaterials; germanium-containing materials; metal, such as aluminum,copper, tungsten, titanium, tantulum, titanium nitride, tantalumnitride, nickel silicide, cobalt silicide, TaC, TaSiN, and/or TaCN;other suitable materials; and/or combinations thereof. In one example,the gate layer comprises a layer of silicon dioxide and a layer ofhigh-k dielectric material. The gate layer may be doped polycrystallinesilicon with the same or different doping. The gate layer may comprise awork function layer. For example, if a P-type work function metal(P-metal) for a PMOS device is desired, TiN, WN, or W may be used. Onthe other hand, if an N-type work function metal (N-metal) for NMOSdevices is desired, TiAl, TiAlN, or TaCN, may be used. In some examples,the work function layer may include doped-conducting metal oxidematerials.

In one example, the substrate 210 comprises a dielectric layer. Thedielectric layer exhibits a dielectric constant ranging between about 1and about 40. In another example, the substrate 210 comprises at leastone of silicon, a metal oxide, or a metal nitride. The composition ofthe substrate may be represented by a formula, MX_(b), where M is ametal or Si, X is an N or O, and b ranges between about 0.4 and 2.5.Examples of substrate compositions including at least one of silicon,metal oxide, or metal nitride include SiO₂, silicon nitride, aluminumoxide, hafnium oxide, lanthanum oxide, other suitable compositions, andcombinations thereof. In yet another example, the substrate 210comprises at least one of a metal, a metal alloy, a metal nitride, ametal sulfide, a metal selenide, a metal oxide, or a metal silicide. Thecomposition of the substrate may be represented by a formula, MX_(a),where M is a metal, X is N, S, Se, O, or Si, and a ranges between 0.4and 2.5. Examples of substrate compositions including at least one ofmetal, metal alloy, or metal nitride/sulfide/selenide/oxide/silicideinclude Ti, Al, Co, Ru, TiN, WN₂, TaN, other suitable compositions,and/or combinations thereof. Also, the substrate 210 may besubstantially conductive or semi-conductive. For example, the electricresistance of the substrate 210 may be less than 10³ ohm-meter.

At steps 104 and 106, a first material layer 212 and a second materiallayer 214 are formed over the substrate 210. Alternatively, the firstmaterial layer 212 may be eliminated and the second material layer 214may be formed over the substrate 210. The first material layer 212comprises a different composition than the second material layer 214.The first and second material layers 212, 214 are coated on thesubstrate 210 to any suitable thickness by any suitable process, such asspin-on coating, chemical vapor deposition (CVD), plasma enhancedchemical vapor deposition (PECVD), atomic layer deposition (ALD),physical vapor deposition (PVD), high density plasma CVD (HDPCVD), othersuitable methods, and/or combinations thereof. The first material layer212 comprises a different optical property than the second materiallayer 214. For example, the first material layer 212 comprisessubstantially different refractive indexes (i.e., n values), extinctioncoefficients (i.e., k values), or T values than the second materiallayer 214. The first and second material layers 212, 214 furthercomprise different etching resistances. The first and/or second materiallayers 212, 214 may comprise at least one etching resistant molecule,such as a low onishi number structure, a double bond, triple bond,silicon, silicon nitride, Ti, TiN, Al, aluminum oxide, and/or SiON.

The first material layer 212 is a patterning layer. The patterning layermay comprise one or more photoresist layers, antireflective coatinglayers (e.g., a top antireflective coating layer (TARC) and/or a bottomantireflective coating layer (BARC)), high-k dielectric layers, gatelayers, hard mask layers, interfacial layers, capping layers,diffusion/barrier layers, dielectric layers, conductive layers, othersuitable layers, and/or combinations thereof. The patterning layer maybe similar to those described above. In one example, the first materiallayer 212 comprises a bottom antireflective coating layer. In anotherexample, the first material layer 212 comprises at least one of an acidlabile molecule, photoacid generator (PAG), quencher, chromophore,crosslinker, surfactant, and/or solvent. This composition may providethe first material layer 212 with a different n value than the secondmaterial layer 214.

The second material layer 214 is a photoresist layer. The photoresistlayer is a positive-type or negative-type resist material and may have amulti-layer structure. One exemplary resist material is a chemicalamplifying (CA) resist. Conventional photoresist layers comprise anon-photodegradable base, which is not photosensitive. Thus, after anexposure process, conventional photoresist layers fail to confine aciddistribution. The non-photodegradable base neutralizes the acidgenerated by a photoacid generator, resulting in a lower than desirableacid and base distribution contrast. This leads to lower patterncontrast after a developing (and/or post-exposure baking) process.

In the present embodiment, the second material layer 214 comprises aphotodegradable base.

The photodegradable base is photosensitive. In contrast to conventionalphotoresist layers, after exposure, the photodegradable base is depletedin the exposure area, resulting in high acid and base distributioncontrast. The photodegradable base does not substantially decrease anacid amount in the exposure areas, yet the acid distribution contrast isreduced by the high base distribution contrast. Thus, thephotodegradable base provides improved profile contrast. Thephotodegradable base includes an amine, which links with one or morefunctional groups comprising substantially delocalizable pi (π)electrons by —C—groups. For example, the photodegradable base isrepresented by the following formula:

Z comprises one or more pendent groups. The pendent groups comprise atleast one of the following: —Cl, —Br, —I, —NO₂, —SO₃—, —H—, —CN, —NCO,—OCN, —CO₂—, —OH, —OR*, —OC(O)CR*, —SR, —SO₂N(R*)₂, —SO₂R*, SOR,—OC(O)R*, —C(O)OR*, —C(O)R*, —Si(OR*)₃, —Si(R*)₃, epoxyl groups, othersuitable groups, and/or combinations thereof. R* is hydrogen, anunbranched group, a branched group, a cyclic group, a noncyclic group, asaturated group, an unsaturated group, an alkyl group, an alkenyl group,an alkynyl group, or other suitable group.

R_(a) comprises the one or more functional groups having a substantiallydelocalizable pi electron. Examples of R_(a) include an aromatic ringgroup, a monovalent functional group, a divalent functional group, or atrivalent functional group. The functional groups comprise at least oneof an alkene, alkyne, —CO—, —C(═O)O—, —S—, —P—, —P(O₂)—, —C(═O)S—, —O—,—N—, —C(═O)N—, —SO₂O—, —SO₂S—, —SO—, —SO₂—, other suitable functionalgroups, and/or combinations thereof.

R_(b) comprises functional groups similar to R_(a). For example, R_(b)can comprise the one or more functional groups having a substantiallydelocalizable pi electron, which include an aromatic ring group, amonovalent functional group, a divalent functional group, or a trivalentfunctional group. The functional groups comprise at least one of analkene, alkyne, —CO—, —C(═O)O—, —S—, —P—, —P(O₂)—, —C(═O)S—, —O—, —N—,—C(═O)N—, —SO₂O—, —SO₂S—, —SO—, —SO₂—, other suitable groups, and/orcombinations thereof. R_(b) may further comprise one of the following:R*, —Cl, —Br, —I, —NO₂, —SO₃—, —H—, —CN, —NCO, —OCN, —CO₂—, —OH, —OR*,—OC(O)CR*, —SR, —SO₂N(R*)₂, —SO₂R*, SOR, —OC(O)R*, —C(O)OR*, —C(O)R*,—Si(OR*)₃, —Si(R*)₃, epoxyl groups, other suitable groups, and/orcombinations thereof. R* is hydrogen, an unbranched group, a branchedgroup, a cyclic group, a noncyclic group, a saturated group, anunsaturated group, an alkyl group, an alkenyl group, an alkynyl group,or other suitable group.

R_(c) comprises an unbranched group, a branched group, a cyclic group, anoncyclic group, a saturated group, an unsaturated group, an alkylgroup, an alkenyl group, an alkynyl group, an aromatic group, othersuitable groups, and/or combinations thereof. R_(c) may further compriseone of the following: —Cl, —Br, —I, —NO₂, —SO₃—, —H—, —CN, —NCO, —OCN,—CO₂—, —OH, —OR*, —OC(O)CR*, —SR, —SO₂N(R*)₂, —SO₂R*, SOR, —OC(O)R*,—C(O)OR*, —C(O)R*, —Si(OR*)₃, —Si(R*)₃, epoxyl groups, other suitablegroups, and/or combinations thereof. R* is hydrogen, an unbranchedgroup, a branched group, a cyclic group, a noncyclic group, a saturatedgroup, an unsaturated group, an alkyl group, an alkenyl group, analkynyl group, or other suitable group.

The second material layer 214 further comprises at least one of apolymer, a photoacid generator (PAG), a quencher (base), an electronacceptor, a chromophore, and/or a solvent. The polymer comprises anorganic or inorganic polymer with a molecular weight betweenapproximately 1000 and 20,000. The polymer may include an acid cleavablepolymer, an acid catalyzed crosslinkable polymer, a polymeric pinacol,and/or other suitable polymer. The electron acceptor may comprise atleast one of the following: ketone, aldehyde, carboxylic acid, ester,amide, carbon dioxide, haloalkane, haloalkene, haloalkyne, alkene,alkyne, aromatic rings, other suitable groups, and/or combinationsthereof. The second material layer 214 may further comprise asurfactant, a photobase generator (PBG), and/or crosslinker.

At step 108, at least one exposure process is performed on the secondmaterial layer 214. The exposure process selectively illuminates thesecond material layer 214 by a radiation beam to form one or moreexposed portions 214A and unexposed portions 214B. The radiation beamused to expose the second material layer 214 may be ultraviolet and/orextended to include other radiation beams, such as ion beam, x-ray,extreme ultraviolet, deep ultraviolet, and other proper radiationenergy. In one example, the second material layer 214 is exposed to awavelength substantially less than 250 nm. The patterned exposed andunexposed portions 214A, 214B are formed by illuminating the secondmaterial layer with a radiation source through one or more photomasks(or reticles) to form an image pattern. The lithography process mayimplement krypton fluoride (KrF) excimer lasers, argon fluoride (ArF)excimer lasers, ArF immersion lithography, ultraviolet (UV) radiation,extreme ultra-violet (EUV) radiation, and/or electron-beam writing(e-beam). The exposing process may also be implemented or replaced byother proper methods such as maskless photolithography, ion-beamwriting, and/or molecular imprint techniques. It is understood that asingle exposure patterning process, double exposure patterning process,or multiple exposure patterning process may be performed. For example,the second material layer 214 may be exposed to a first wavelength, andthen, subsequently exposed to a second wavelength.

As noted above, the basicity of the second material layer 214 isdecreased after the exposure process. Particularly, the second materiallayer comprises at least a photodegradable base and an electronacceptor, wherein the photodegradable amine (base) is linked to one ormore functional groups comprising substantially delocalizable pielectrons by —C—. The highest occupied molecular orbital (HOMO) of thephotodegradable base lies between the HOMO and lowest unoccupiedmolecular orbital (LUMO) of the electron acceptor. The electron acceptorHOMO is lower than the photodegradable base HOMO, and the electronacceptor LUMO is higher than the photodegradable base HOMO. Thus, afterexposure, one of two reactions can occur: (1) an electron of thephotodegradable base may be excited to the LUMO and transferred to theelectron acceptor (i.e., the stronger base amine changes to a weak baseimine) or (2) an electron of the electron acceptor may be excited to theLUMO and transferred to the photodegradable base (i.e., after thechemical reaction, the amine becomes a conjugated imine, decreasing itsbasicity). The decrease basicity in the exposed regions of the secondmaterial layer 214 provide improved acid/base distribution contrast,resulting in an improved pattern profile.

Subsequently, the second material layer 214 may be subjected to apost-exposure bake (PEB) process. After a pattern exposure and/orpost-exposure bake (PEB) process, the PAG in the second material layer214 (i.e., photoresist) may produce an acid and thus increase ordecrease its solubility. The solubility may be increased for positivetone resist (i.e., the acid will cleave an acid cleavable polymer,resulting in the polymer becoming more hydrophilic) and decreased fornegative tone resist (i.e., the acid will catalyze an acid catalyzedcrosslinkable polymer or cause a polymeric pinnacle to undergo pinacolrearrangement, resulting in the polymer becoming more hydrophobic).

At step 110, the second material layer 214 is developed to form apattern in the second material layer 214 by any suitable process. Adeveloping solution may be utilized to remove portions of the secondmaterial layer 214, such as tetramethylammonium hydroxide (TMAH). Anyconcentration level of TMAH developer solution may be utilized, such asapproximately 2.38% TMAH developer solution. The developing solution mayremove the exposed or unexposed portions 214A, 214B depending on theresist type. For example, in the present embodiment, the second materiallayer 214 comprises a negative-type resist, so the exposed portions 214Aare not dissolved by the developing solution and remain over the firstmaterial layer 212 (or substrate 210). If the second material layer 214comprises a positive-type resist, the exposed portions 214A would bedissolved by the developing solution, leaving the unexposed portions214B.

The remaining exposed portions 214A (or unexposed portions 214B) definea pattern. The pattern contains one or more openings, wherein portionsof the underlying first material layer 212 (or substrate 210) areexposed. The pattern provides improved profile, critical dimensionuniformity, and/or circularity. It is understood that subsequentprocessing may include removing the exposed portions of the firstmaterial layer 212 and/or substrate 210 within the openings.Alternatively, metal deposition, ion implantation, or other processescan be carried out over/on the first material layer 212 and/or substrate210. The patterned second material layer 214 may then be removed orstripped and subsequent processing may continue.

In summary, the disclosed embodiments may provide a method forfabricating an integrated circuit device utilizing a photoresist layercomprising a photodegradable base. The photodegradable base is an aminelinked with at least one functional group, which comprises substantiallydelocalizable pi electrons by a —C— group. The photodegradable basedecreases within exposed areas of a photoresist layer, providingimproved acid distribution and base distribution contrast, resultingultimately in improved profile contrast. The disclosed embodiments mayprovide one or more advantages, such as improved lithography resolution,patterning profiles, critical dimension uniformity, and/or circularity.Also, the disclosed method and photoresist material provide reducediso/dense bias. It is understood that different embodiments may havedifferent advantages, and that no particular advantage is necessarilyrequired of all embodiments.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

1. A photoresist material used for semiconductor device patterning, thephotoresist material comprising: a polymer; a photoacid generator; aquencher base; an electron acceptor; and a photodegradable base.
 2. Thephotoresist material of claim 1 further comprising at least one of achromophore, a solvent, a surfactant, a photobase generator, and/or acrosslinker.
 3. The photoresist material of claim 1 wherein thephotodegradable base comprises an amine linked with a functional groupcomprising substantially delocalizable pi electrons by a —C— group. 4.The photoresist material of claim 1 wherein the photodegradable base isrepresented by the formula:

wherein R_(a) comprises one of an aromatic ring, a monovalent functionalgroup, a divalent functional group, or a trivalent functional group,R_(b) comprises one of an aromatic ring, a monovalent functional group,a divalent functional group, or a trivalent functional group, R_(c)comprises an unbranched group, a branched group, a cyclic group, anoncyclic group, a saturated group, an unsaturated group, an alkylgroup, an alkenyl group, an alkynyl group, or an aromatic group, and Zis a pendant group.
 5. The photoresist material of claim 4 wherein thependant group is selected from the group consisting of: —Cl, —Br, —I,—NO₂, —SO₃—, —H—, —CN, —NCO, —OCN, —CO₂—, —OH, —OR*, —OC(O)CR*, —SR,—SO₂N(R*)₂, —SO₂R*, SOR, —OC(O)R*, —C(O)OR*, —C(O)R*, —Si(OR*)₃,—Si(R*)₃, or an epoxyl group.
 6. The method of claim 5 wherein R*comprises at least one of hydrogen, an unbranched group, a branchedgroup, a cyclic group, a noncyclic group, a saturated group, anunsaturated group, an alkyl group, an alkenyl group, or an alkynylgroup.
 7. The photoresist material of claim 4 wherein the functionalgroups of R_(a) comprise at least one of an alkene, alkyne, —CO—,—C(═O)O—, —S—, —P—, —P(O₂)—, —C(═O)S—, —O—, —N—, —C(═O)N—, —SO₂O—,—SO₂S—, —SO—, or —SO₂—.
 8. The photoresist material of claim 4 whereinR_(b) and/or R_(c) comprise at least one of —Cl, —Br, —I, —NO₂, —SO₃—,—H—, —CN, —NCO, —OCN, —CO₂—, —OH, —OR*, —OC(O)CR*, —SR, —SO₂N(R*)₂,—SO₂R*, SOR, —OC(O)R*, —C(O)OR*, —C(O)R*, —Si(OR*)₃, —Si(R*)₃, or anepoxyl group.
 9. The photoresist material of claim 8 wherein R*comprises at least one of hydrogen, an unbranched group, a branchedgroup, a cyclic group, a noncyclic group, a saturated group, anunsaturated group, an alkyl group, an alkenyl group, or an alkynylgroup.
 10. The photoresist material of claim 1 wherein the electronacceptor comprises at least one of a ketone, aldehyde, carboxylic acid,ester, amide, carbon dioxide, haloalkane, haloalkene, haloalkyne,alkene, alkyne, aromatic rings, other suitable groups, and/orcombinations thereof.
 11. A method for forming a pattern on asemiconductor device, the method comprising: providing a substrate;forming a first material layer over the substrate; forming a secondmaterial layer over the first material layer, wherein the secondmaterial layer comprises a photodegradable base material; and exposingone or more portions of the second material layer.
 12. The method ofclaim 11 wherein forming the second material layer comprises depositinga photoresist layer with a photodegradable base material comprising anamine linked to at least one functional group having substantiallydelocalizable pi electrons by a —C— group.
 13. The method of claim 11further comprising: performing a post-exposure baking process on thesecond material layer; and developing the second material layer to formthe pattern.
 14. The method of claim 13 wherein developing the secondmaterial layer to form the pattern comprises utilizing a basic solutionincluding tetramethylammonium hydroxide (TMAH).
 15. The method of claim11 wherein exposing one or more portions of the second material layercomprises causing the photodegradable base to decrease its basicity. 16.The method of claim 11 wherein exposing one or more portions of thesecond material layer comprises exposing the second material layer toradiation having a wavelength substantially less than 250 nm.
 17. Themethod of claim 11 wherein the photodegradable base is represented bythe formula:

wherein R_(a) comprises one of an aromatic ring, a monovalent functionalgroup, a divalent functional group, or a trivalent functional group,R_(b) comprises one of an aromatic ring, a monovalent functional group,a divalent functional group, or a trivalent functional group, R_(c)comprises an unbranched group, a branched group, a cyclic group, anoncyclic group, a saturated group, an unsaturated group, an alkylgroup, an alkenyl group, an alkynyl group, or an aromatic group, and Zis a pendant group.
 18. The method of claim 17 wherein the pendant groupis selected from the group consisting of: —Cl, —Br, —I, —NO₂, —SO₃—,—H—, —CN, —NCO, —OCN, —CO₂—, —OH, —OR*, —OC(O)CR*, —SR, —SO₂N(R*)₂,—SO₂R*, SOR, —OC(O)R*, —C(O)OR*, —C(O)R*, —Si(OR*)₃, —Si(R*)₃, or anepoxyl group.
 19. The method of claim 18 wherein R* comprises at leastone of hydrogen, an unbranched group, a branched group, a cyclic group,a noncyclic group, a saturated group, an unsaturated group, an alkylgroup, an alkenyl group, or an alkynyl group.